Base-promoted reaction of O-sulfonylated hydroxamic acids with nucleophiles. A new method for the synthesis of .alpha.-substituted amides
摘要:
Treatment of a series of hydroxamic acids 2 with mesyl chloride in the presence of 2 equiv of triethylamine at 0-degrees-C gives 2-chloroamides 3 in good yields. Use of a single equivalent of triethylamine gives the (N-mesyl-oxy)amides 1, which are versatile synthetic intermediates as they can be readily converted to 2-bromoamides 4 with lithium bromide and triethylamine and to 2-hydroxyamides 5 with triethylamine in aqueous acetonitrile.
A catalyst‐ and additive‐free chemoselective transfer hydrogenation of α‐keto amides to α‐hydroxy amides is easily achieved by using sodium formate as a hydrogen source. Control experiments suggest that the NH group of α‐keto amides is crucial for the chemoselective reduction through the formation of hydrogen bonds.
A Cs2CO3-catalyzed hydrosilylation reaction of α-keto amides that proceeds through the in situ formation of MeSiH3 has been developed by using inexpensive polymethylhydrosiloxane in 2-methyltetrahydrofuran (2-MeTHF) as the solvent. A wide range of aryl and alkyl α-keto amides, prepared from anilines and alkylamines, were subjected to the hydrosilylation conditions to afford α-hydroxy amides in moderate
通过在2-甲基四氢呋喃(2-MeTHF)中使用廉价的聚甲基氢硅氧烷,开发了通过MeSiH 3原位形成的α-酮酰胺的Cs 2 CO 3催化的氢化硅烷化反应。将由苯胺和烷基胺制得的各种芳基和烷基α-酮酰胺置于氢化硅烷化条件下,以中等至极好的收率得到α-羟基酰胺。将该无过渡金属的方案应用于化学选择性氢化硅烷化反应,其中与简单酮相比,α-酮酰胺官能团的羰基发生还原,并进一步扩展至克级规程。
Alkyl Halide-Free Heteroatom Alkylation and Epoxidation Facilitated by a Recyclable Polymer-Supported Oxidant for the In-Flow Preparation of Diazo Compounds
作者:Simon M. Nicolle、Christopher J. Hayes、Christopher J. Moody
DOI:10.1002/chem.201500118
日期:2015.3.16
simple ketones via diazocompounds, including diazo‐amides and ‐phosphonates, using a recyclable reagent in‐flow, are transient but versatile electrophiles for heteroatomalkylation reactions and for epoxide formation. The method produces no organic waste, with the only by‐products being water, KI and nitrogen, without the attendant hazards of isolation of intermediate diazocompounds.
Lewis acid-catalyzed formation of Ugi four-component reaction product from Passerini three-component reaction system without an added amine
作者:Wei-Min Dai、Huoming Li
DOI:10.1016/j.tet.2007.10.050
日期:2007.12
In the presence of a Lewis acid the phenol-Passerini three-component reaction (phenol-P-3CR) system is found to deliver a product of the phenol-Ugi four-componentreaction (phenol-U-4CR). It is the first demonstration of an isocyanide as an amine equivalent in isocyanide-based multicomponent reactions (IMCRs). In general, by using Ti(O-i-Pr)4 in MeOH both phenol-U-4CR and U-4CR products are synthesized